Add Domain project and shifted handlers to application.

wolverine/a-frame-architecture/FinancialApi.Application/ApplyFeeHandler.cs

@@ -1,28 +1,28 @@
-using FinancialApi.Application;
+using FinancialApi.Domain;
-using Microsoft.EntityFrameworkCore;
 using Wolverine.Attributes;
 using Wolverine.Persistence;
 
-namespace FinancialApi.Infrastructure;
+namespace FinancialApi.Application;
 
 public record ApplyFeeCommand(int AccountId, decimal Amount);
 
-public record FeePair(Account CustomerAccount, Account RevenueAccount);
-
 public record FeeAppliedEvent(int AccountId, decimal Amount);
 
 public static class ApplyFeeHandler
 {
-    public static async Task<FeePair?> LoadAsync(
+    public static async Task<(Account, Account)> LoadAsync(
         ApplyFeeCommand cmd,
-        AccountDbContext db)
+        IAccountQuery query)
     {
-        var customer = await db.Accounts.AsNoTracking().SingleOrDefaultAsync(x => x.Id == cmd.AccountId);
+        var source = await query.FindByIdAsync(cmd.AccountId);
-        var revenue = await db.Accounts.AsNoTracking().SingleOrDefaultAsync(x => x.Id == 99999);
+        var dest = await query.FindByIdAsync(99999);
-        return (customer == null || revenue == null) ? null : new FeePair(customer, revenue);
+        if (source == null || dest == null)
+        {
+            throw new InvalidOperationException($"Cannot process transfer. Account(s) not found.");
+        }
+        return (source, dest);
     }
 
-    [Transactional]
     public static (
         IStorageAction<Account> CustomerWrite,
         IStorageAction<Account> RevenueWrite,
@@ -31,15 +31,16 @@ public static class ApplyFeeHandler
         )
         Handle(
             ApplyFeeCommand cmd,
-            FeePair pair
+            Account source,
+            Account dest
         )
     {
-        var updatedCustomer = pair.CustomerAccount.ApplyPosting(cmd.Amount, EntryType.Debit);
+        var updatedSource = source.ApplyPosting(cmd.Amount, EntryType.Debit);
-        var updatedRevenue = pair.RevenueAccount.ApplyPosting(cmd.Amount, EntryType.Credit);
+        var updatedRevenue = dest.ApplyPosting(cmd.Amount, EntryType.Credit);
         var lines = new List<JournalLine>
         {
-            new(pair.CustomerAccount.Id, cmd.Amount, EntryType.Debit),
+            new(updatedSource.Id, cmd.Amount, EntryType.Debit),
-            new(9999, cmd.Amount, EntryType.Credit)
+            new(updatedRevenue.Id, cmd.Amount, EntryType.Credit)
         };
         var journalEntry = BalancedJournal.Create(Guid.NewGuid(),
             $"Service Fee Applied: {cmd.Amount} to Account {cmd.AccountId}",
@@ -48,7 +49,7 @@ public static class ApplyFeeHandler
         var @event = new FeeAppliedEvent(cmd.AccountId, cmd.Amount);
 
         return (
-            Storage.Update(updatedCustomer),
+            Storage.Update(updatedSource),
             Storage.Update(updatedRevenue),
             Storage.Insert(journalEntry.Entry),
             @event

wolverine/a-frame-architecture/FinancialApi.Application/FinancialApi.Application.csproj

@@ -6,4 +6,14 @@
         <Nullable>enable</Nullable>
     </PropertyGroup>
 
+    <ItemGroup>
+      <ProjectReference Include="..\FinancialApi.Domain\FinancialApi.Domain.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <Reference Include="Wolverine">
+        <HintPath>..\..\..\..\..\..\.nuget\packages\wolverinefx\6.18.0\lib\net10.0\Wolverine.dll</HintPath>
+      </Reference>
+    </ItemGroup>
+
 </Project>

wolverine/a-frame-architecture/FinancialApi.Application/TransferFundsHandler.cs

@@ -1,30 +1,32 @@
-using FinancialApi.Application;
+using FinancialApi.Domain;
-using Microsoft.EntityFrameworkCore;
 using Wolverine.Attributes;
 using Wolverine.Persistence;
 
-namespace FinancialApi.Infrastructure;
+namespace FinancialApi.Application;
+
+public interface IAccountQuery
+{
+    Task<Account?> FindByIdAsync(int id);
+}
 
 public record TransferFundsCommand(int SourceAccountId, int DestinationAccountId, decimal Amount);
 
 public record FundsTransferredEvent(int SourceAccountId, int DestinationAccountId, decimal Amount);
 
-// A simple container to pass our loaded entities into the pure function
 public record TransferPair(Account Source, Account Destination);
 
 public static class TransferFundsHandler
 {
-    public static async Task<TransferPair?> LoadAsync(TransferFundsCommand cmd, AccountDbContext db)
+    public static async Task<TransferPair?> LoadAsync(TransferFundsCommand cmd, IAccountQuery query)
     {
-        var source = await db.Accounts.AsNoTracking().FirstOrDefaultAsync(x => x.Id == cmd.SourceAccountId);
+        var source = await query.FindByIdAsync(cmd.SourceAccountId);
-        var dest = await db.Accounts.AsNoTracking().FirstOrDefaultAsync(x => x.Id == cmd.DestinationAccountId);
+        var dest = await query.FindByIdAsync(cmd.DestinationAccountId);
 
-        if (source == null || dest == null) return null; // Wolverine drops into a 404/Problem if null
+        if (source == null || dest == null) return null;
 
         return new TransferPair(source, dest);
     }
 
-    [Transactional]
     public static (
         IStorageAction<Account> SourceWrite,
         IStorageAction<Account> DestWrite,

wolverine/a-frame-architecture/FinancialApi.Domain/Account.cs

@@ -1,4 +1,4 @@
-namespace FinancialApi.Application;
+namespace FinancialApi.Domain;
 
 public record Account(int Id, decimal Balance, string AccountType)
 {
@@ -18,7 +18,6 @@ public record Account(int Id, decimal Balance, string AccountType)
         {
             newBalance = entryType == EntryType.Debit ? newBalance - amount : newBalance + amount;
         }
-        
 
         if (newBalance < 0 && AccountType == "Liability")
         {
@@ -28,21 +27,6 @@ public record Account(int Id, decimal Balance, string AccountType)
         return this with { Balance = newBalance };
     }
 
-    public Account ApplyFee(decimal amount)
-    {
-        if (amount <= 0)
-        {
-            throw new ArgumentException("Fee must be positive.");
-        }
-
-        if (Balance - amount < 0)
-        {
-            throw new InvalidOperationException("Insufficient funds.");
-        }
-
-        return this with { Balance = Balance - amount };
-    }
-
     public Account Debit(decimal amount)
     {
         if (amount <= 0)

wolverine/a-frame-architecture/FinancialApi.Domain/BalancedJournal.cs

@@ -1,4 +1,4 @@
-namespace FinancialApi.Application;
+namespace FinancialApi.Domain;
 
 public record BalancedJournal
 {

wolverine/a-frame-architecture/FinancialApi.Domain/EntryType.cs

@@ -1,4 +1,4 @@
-namespace FinancialApi.Application;
+namespace FinancialApi.Domain;
 
 public enum EntryType
 {

wolverine/a-frame-architecture/FinancialApi.Domain/FinancialApi.Domain.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

wolverine/a-frame-architecture/FinancialApi.Domain/JournalEntry.cs

@@ -1,4 +1,4 @@
-namespace FinancialApi.Application;
+namespace FinancialApi.Domain;
 
 public record JournalEntry
 {
@@ -7,10 +7,6 @@ public record JournalEntry
     public DateTimeOffset CreatedAt { get; init; }
     public List<JournalLine> Lines { get; init; } = [];
 
-    private JournalEntry()
-    {
-    }
-
     internal JournalEntry(Guid id, string description, DateTimeOffset createdAt, List<JournalLine> lines)
     {
         Lines = lines;

wolverine/a-frame-architecture/FinancialApi.Domain/JournalLine.cs

@@ -1,3 +1,3 @@
-namespace FinancialApi.Application;
+namespace FinancialApi.Domain;
 
 public record JournalLine(int AccountId, decimal Amount, EntryType Type);

wolverine/a-frame-architecture/FinancialApi.Infrastructure/AccountDbContext.cs

@@ -1,4 +1,4 @@
-using FinancialApi.Application;
+using FinancialApi.Domain;
 using Microsoft.EntityFrameworkCore;
 
 namespace FinancialApi.Infrastructure;

wolverine/a-frame-architecture/FinancialApi.Infrastructure/AccountQuery.cs

@@ -0,0 +1,13 @@
+using FinancialApi.Application;
+using FinancialApi.Domain;
+using Microsoft.EntityFrameworkCore;
+
+namespace FinancialApi.Infrastructure;
+
+public class AccountQuery(AccountDbContext db) : IAccountQuery
+{
+    public Task<Account?> FindByIdAsync(int id)
+    {
+        return db.Accounts.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id);
+    }
+}

wolverine/a-frame-architecture/FinancialApi.Infrastructure/FinancialApi.Infrastructure.csproj

@@ -8,6 +8,7 @@
 
     <ItemGroup>
       <ProjectReference Include="..\FinancialApi.Application\FinancialApi.Application.csproj" />
+      <ProjectReference Include="..\FinancialApi.Domain\FinancialApi.Domain.csproj" />
     </ItemGroup>
 
     <ItemGroup>

wolverine/a-frame-architecture/FinancialApi.Infrastructure/Migrations/20260715100428_UpdateAccountBalances.Designer.cs

@@ -0,0 +1,115 @@
+// <auto-generated />
+using System;
+using FinancialApi.Infrastructure;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace FinancialApi.Infrastructure.Migrations
+{
+    [DbContext(typeof(AccountDbContext))]
+    [Migration("20260715100428_UpdateAccountBalances")]
+    partial class UpdateAccountBalances
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "10.0.9");
+
+            modelBuilder.Entity("FinancialApi.Application.Account", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("AccountType")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<decimal>("Balance")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Accounts");
+
+                    b.HasData(
+                        new
+                        {
+                            Id = 1,
+                            AccountType = "Credit",
+                            Balance = 10000000.00m
+                        },
+                        new
+                        {
+                            Id = 2,
+                            AccountType = "Liability",
+                            Balance = 50000000.00m
+                        },
+                        new
+                        {
+                            Id = 99999,
+                            AccountType = "Revenue",
+                            Balance = 0.00m
+                        });
+                });
+
+            modelBuilder.Entity("FinancialApi.Application.JournalEntry", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("JournalEntries");
+                });
+
+            modelBuilder.Entity("FinancialApi.Application.JournalEntry", b =>
+                {
+                    b.OwnsMany("FinancialApi.Application.JournalLine", "Lines", b1 =>
+                        {
+                            b1.Property<int>("Id")
+                                .ValueGeneratedOnAdd()
+                                .HasColumnType("INTEGER");
+
+                            b1.Property<int>("AccountId")
+                                .HasColumnType("INTEGER");
+
+                            b1.Property<decimal>("Amount")
+                                .HasColumnType("TEXT");
+
+                            b1.Property<Guid>("JournalEntryId")
+                                .HasColumnType("TEXT");
+
+                            b1.Property<string>("Type")
+                                .IsRequired()
+                                .HasColumnType("TEXT");
+
+                            b1.HasKey("Id");
+
+                            b1.HasIndex("JournalEntryId");
+
+                            b1.ToTable("JournalLine");
+
+                            b1.WithOwner()
+                                .HasForeignKey("JournalEntryId");
+                        });
+
+                    b.Navigation("Lines");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

wolverine/a-frame-architecture/FinancialApi/DomainExceptionHandler.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Diagnostics;
+using Microsoft.AspNetCore.Mvc;
+
+namespace FinancialApi;
+
+public class DomainExceptionHandler : IExceptionHandler
+{
+    public async ValueTask<bool> TryHandleAsync(
+        HttpContext httpContext, 
+        Exception exception, 
+        CancellationToken cancellationToken)
+    {
+        // Only intercept our specific domain/validation exceptions
+        if (exception is InvalidOperationException or ArgumentException)
+        {
+            var problemDetails = new ProblemDetails
+            {
+                Status = StatusCodes.Status400BadRequest,
+                Title = "Domain Validation Error",
+                Detail = exception.Message,
+                Type = "https://datatracker.ietf.org/doc/html/rfc7231#section-6.5.1"
+            };
+
+            httpContext.Response.StatusCode = problemDetails.Status.Value;
+            await httpContext.Response.WriteAsJsonAsync(problemDetails, cancellationToken);
+            
+            return true;
+        }
+
+        return false; 
+    }
+}

wolverine/a-frame-architecture/FinancialApi/Program.cs

@@ -1,4 +1,5 @@
 using FinancialApi;
+using FinancialApi.Application;
 using FinancialApi.Infrastructure;
 using FinancialApi.ServiceDefaults;
 using JasperFx.CodeGeneration;
@@ -11,11 +12,16 @@ using Wolverine.Sqlite;
 
 var builder = WebApplication.CreateBuilder(args);
 
+builder.Services.AddExceptionHandler<DomainExceptionHandler>();
+builder.Services.AddProblemDetails();
+
 var connectionString = "Data Source=demo.db";
 
 builder.Services.AddDbContext<AccountDbContext>(options =>
     options.UseSqlite(connectionString));
 
+builder.Services.AddScoped<IAccountQuery, AccountQuery>();
+
 // Add services to the container.
 // Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
 builder.Services.AddOpenApi();
@@ -33,6 +39,8 @@ builder.Host.UseResourceSetupOnStartup();
 
 var app = builder.Build();
 
+app.UseExceptionHandler();
+
 using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<AccountDbContext>();

wolverine/a-frame-architecture/a-frame-architecture.sln

@@ -8,6 +8,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FinancialApi.Application",
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FinancialApi.Infrastructure", "FinancialApi.Infrastructure\FinancialApi.Infrastructure.csproj", "{6AB36AB5-05BD-41C8-9498-63EBDFAF8114}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "FinancialApi.Domain", "FinancialApi.Domain\FinancialApi.Domain.csproj", "{2DB493D2-1C96-4F7C-9AB6-2846A92860B9}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -30,5 +32,9 @@ Global
 		{6AB36AB5-05BD-41C8-9498-63EBDFAF8114}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6AB36AB5-05BD-41C8-9498-63EBDFAF8114}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{6AB36AB5-05BD-41C8-9498-63EBDFAF8114}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2DB493D2-1C96-4F7C-9AB6-2846A92860B9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2DB493D2-1C96-4F7C-9AB6-2846A92860B9}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2DB493D2-1C96-4F7C-9AB6-2846A92860B9}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2DB493D2-1C96-4F7C-9AB6-2846A92860B9}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal